There are a number of medical procedures which involve the frequent introduction of a medicinal liquid or biological fluid into a selected body area of a patient or the withdrawal of a medicinal or biological fluid from a patient. While needles can be used for such purposes where the area of the body is close to the surface, for example to inject a fluid into the bloodstream, there are some treatments, such as peritoneal dialysis, where needles cannot reach and it is required to surgically implant a catheter in order to introduce the desired fluid and for the removal thereof. Even for procedures where a needle may be utilized, repeated puncturing of veins with needles results in damage to the veins which makes it difficult to find a suitable site for further punctures. This results in pain and anxiety to the patient, both of which are undesirable. Further, if a needle remains in the patient for an extended period of time, the needle can infiltrate, preventing proper introduction of the substance, causing extreme discomfort to the patient, and possibly leading to infection or other injury to the patient. For these reasons, patients who are going to be receiving frequent medical procedures involving the introduction or withdrawal of fluids, such as cancer patients undergoing chemotherapy, frequently have catheters surgically implanted which may be used for the introduction of the medicinal fluid.
However, surgically implanted catheters are usually open on the proximal end and, while some sort of temporary seal may be put on the catheter when not in use, the catheters basically provide an open channel into the patient's body. As a result, these catheters expose the patient to infection, and even with careful cleaning and sterilization of the ends of these catheters at regular intervals and after use, using various means such as ultraviolet or microwave radiation, the infection rate on patients having such catheters is still relatively high. With cleaning, but without sterilization, an average of sixty percent of patients having such catheters for peritoneal dialysis develop infections during the first year.
The risk of infection with surgically implanted catheters and the time, trouble and expense involved in the frequent cleaning and sterilization of such catheters in order to minimize infection, has resulted in surgically implanted catheters being used only in limited situations, such as peritoneal dialysis, where there is no other feasible way to reach the desired area of the body, or in situations where the condition of the patient's veins makes it nonfeasible to continue treatment by use of needles. However, if a procedure could be developed which would permit such catheters to be permanently sealed, thus minimizing infection, while still permitting medicinal or biologic fluids to be transferred therethrough, such catheters could be used far more extensively, not only for peritoneal dialysis, but for cancer patients undergoing chemotherapy, patients in hospitals requiring frequent introduction of blood or intravenous substances, diabetics requiring regular shots of insulin and the like. Such a procedure would also be highly advantage for peritoneal dialysis patients, cancer patients and others currently having implanted catheters in that the risk of infection could be substantially reduced while the time and expense involved in cleaning and sterilizing the catheters would be virtually eliminated.
One way of solving the above problem is to seal the catheter with a rubber seal as is used on bottles containing an injectable substance or a standard compressible rubber ball seal. A hypodermic needle, which could be either a standard needle or one especially designed for this purpose, could be utilized to pierce the seal and the desired medicinal or biologic fluids could be introduced or withdrawn through the needle. On the withdrawal of the needle, the seal would immediately close behind the needle preventing infection from getting in, and an alcohol wipe could be used over the seal as the needle is withdrawn or just after the needle is withdrawn to further reduce the possibility of infection. The wiping action of the seal on the needle would also tend to clean the needle on introduction to further reduce the possibility of an infectious agent being introduced.
However, there are two potential problems in using such a rubber seal and needle arrangement. First, while such seals may be punctured a substantial number of times before they lose the elasticity to reseal, the number of times the seal may be punctured varying somewhat with the gauge of needle used, to minimize infection it is preferable that the seal not be used to any way near its maximum theoretical number of punctures. Thus, for a seal with a theoretical life of one hundred and eighty punctures, it might be necessary to replace the seal after for example one hundred to one hundred and fifty punctures. Since procedures such as peritoneal dialysis may require as many as four punctures a day, this would mean that a single seal would only last for approximately one month. Since a patient should not be subjected to a surgical procedure, even a relatively simple surgical procedure, on a monthly basis if such can be avoided, it is desirable that the seal either be replaceable without requiring surgical implantation of a new catheter, or that procedures be provided for extending the life of the seal for several years.
The second potential problem is that a reasonably flow rate may be required in order to permit the medical procedure to be completed within an acceptable time period. For example, for peritoneal dialysis, it is required that two liters of dialysate be transferred over a twenty- to thirty-minute time period, requiring a flow rate in the 60-100 ml/min range. Relying on gravity, or other similar means, it may not be possible to achieve the desired flow rate through a standard needle. A means must therefore be provided for enhancing the flow rate of the selected fluid through the needle so that a desired flow rate can be achieved.
A need therefore exists for a method and apparatus for providing a seal for a surgically implanted catheter which seal permits desired fluids to pass therethrough at a required flow rate. Such seal should either be replaceable without requiring surgical procedure or the life of the seal should be extended to a point where surgical reimplantation or replacement of the catheter is not required for several years.